Peptifact

IGF-1 LR3 Dosage: We Read All 44 Papers and Not One Is a Human Study

IGF-1 LR3 has no label, no trial registration and 44 indexed papers — every one of them in cells, livestock or rodents. The nearest approved comparator is dosed per kilogram, twice daily, with glucose monitoring.

Robert F · Edited by Caroline S · Published 2026-09-11

Illustration: A clear glass vial and a pipette on a white lab bench in soft daylight.
Illustration

Most pages in this catalogue report a thin file. IGF-1 LR3's file is not thin — 44 indexed papers is a respectable number for a research compound. It is simply about something else. We retrieved all 44 records and read the titles, and the result is unambiguous: not one of them is a study in humans.

This page reports what the sources state and does not recommend anything. Our page on the questions we ask of any dosage figure sets out what separates a label figure from a convention. How brands appear on this site is set out on our disclosure page.

What the molecule actually is

IGF-1 LR3 — written variously as Long R3 IGF-1, IGF-I LR3 or LR3 IGF-1 — is not insulin-like growth factor 1. It is an engineered analogue with two changes: an arginine substitution at position 3, and a 13-amino-acid N-terminal extension.

Both changes serve one purpose: reducing binding to the IGF-binding proteins that normally capture circulating IGF-1. In a culture dish, where binding proteins secreted by the cells would otherwise mop up the supplement, that makes the analogue far more potent per microgram than native IGF-1. It is the reason the molecule exists.

It is also the reason a figure worked out for IGF-1 does not transfer. The two molecules differ specifically in how much free compound a given quantity yields.

What does not exist

  • DailyMed: zero records on 2026-09-11. No approved product contains this analogue, so no labelled dose, no maximum, no reviewed safety position.
  • ClinicalTrials.gov: no studies. Not a completed one, not a withdrawn one, none.
  • PubMed randomised-controlled-trial filter: zero.

Reading all 44

A title-and-abstract search for "IGF-1 LR3"[tiab] OR "IGF-I LR3"[tiab] OR "LR3 IGF"[tiab] OR "Long R3 IGF-1"[tiab] returned 44 records, spanning 1993 to 2026. Forty-four is small enough to read in full, so we did.

Group Approx. count What they are
Reproductive / ovarian cell culture 14 Granulosa, theca and cumulus cell work in serum-free systems — bovine, ovine, porcine, human endometrial
In vivo livestock 9 Fetal and neonatal sheep infusions, beef heifers, neonatal pigs, turkey satellite cells, sheep rumen epithelium
Cancer and cell lines 5 Breast epithelial and breast cancer cells, receptor-inhibitor studies, a drug conjugate
Rodent 4 Diabetic rats, tumour-bearing rats, atherosclerosis in mice, intranasal treatment in a cerebral amyloid model
Protein expression / bioprocess 3 CHO cell glycosylation, Pichia pastoris expression, transient production methodology
Muscle and satellite cell 3 Bovine and turkey satellite cells, skeletal-muscle binding protein expression
Reviews and other 6 Intestinal growth review, wound clearance, uterine signalling, a 2026 review of GH–IGF1-axis performance peptides
Human studies 0 —

The single largest group is cell culture, which is what the molecule was built for. The second largest is farm animals.

The newest primary result is negative

The most recent primary in vivo work is a run of fetal-sheep infusion studies, and the 2025 entry in the American Journal of Physiology — Endocrinology and Metabolism is titled, plainly: "IGF-1 LR3 does not promote growth in late-gestation growth-restricted fetal sheep."

That is worth stating because a compound sold on a growth premise has, as the latest primary finding in its indexed file, a study reporting no growth effect in the model it was tested in.

A related 2023 paper in the Journal of Developmental Origins of Health and Disease examined attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion into fetal sheep. Neither result establishes anything about a human. Both point at the same axis.

What a reviewed IGF-1 dose looks like

There is an approved IGF-1 product — a different molecule, for a different population. INCRELEX (mecasermin), recombinant human IGF-1, is indicated for growth failure in children two and older with severe primary IGF-1 deficiency, or a growth-hormone gene deletion with neutralising antibodies to GH.

Item What the INCRELEX label states
Starting dose 0.04–0.08 mg/kg body weight twice daily, subcutaneous
Titration Increase by 0.04 mg/kg per dose after ≥ 1 week if tolerated
Maximum 0.12 mg/kg twice daily
Timing Shortly before or after (± 20 min) a meal or snack
Monitoring Preprandial glucose monitoring at initiation and until a tolerated dose is established
Supervision A physician experienced in the diagnosis and management of the condition

The label's warnings are the part most worth reading beside a research page: severe hypoglycaemia leading to hypoglycaemic seizures, a contraindication in active or suspected malignant neoplasia, and warnings for intracranial hypertension, tonsillar and adenoidal hypertrophy, slipped capital femoral epiphysis and progression of pre-existing scoliosis. Patients are advised to avoid driving or exercise for two to three hours after dosing.

The shape of that figure is the point. A reviewed IGF-1 dose is per kilogram, twice daily, titrated over weeks, taken with food, under glucose monitoring, by a specialist. The figures that circulate for the analogue are flat daily microgram numbers with no weight term, no titration and no monitoring — and they are for a molecule engineered to escape the binding proteins that would have damped it.

What the sources state as a quantity

Figure stated Route Where it comes from
20–50 µg per day Subcutaneous Vendor and protocol pages; no stated origin
Post-training timing conventions — Forum convention; no study located

We could not find a source stating where these originated. They appear across pages in near-identical form, which is the signature of a convention that propagated rather than one that was derived.

The arithmetic, if a figure is being converted

A 1 mg vial in 1 mL of bacteriostatic water gives 1,000 µg/mL. A stated 20 µg is 0.02 mL — 2 units on a U-100 insulin syringe. The same vial in 2 mL halves the concentration and doubles that to 4 units.

At two units, the graduation interval and the syringe's dead space stop being rounding errors and become a meaningful share of the quantity. Our page on syringe graduations and dead space works through where dead space goes at small volumes, and our reconstitution page carries the arithmetic for other combinations.

What is not established

  • No approved label anywhere mentions this analogue.
  • No trial registration anywhere, so no protocol or results record exists to check a claim against.
  • No human study in the indexed literature, so the human dose-response relationship cannot be examined.
  • No stated origin for the circulating microgram figures.
  • The latest primary in vivo result is a negative one in the fetal-sheep model.
  • Whether the approved product's warnings transfer is unknown. The hypoglycaemia, neoplasia and growth-plate warnings on INCRELEX attach to native IGF-1 in a specific paediatric population. Nobody has established what they mean for a binding-protein-resistant analogue in an adult, because nobody has published the study.

What a reader can check in five minutes

  1. Search DailyMed for IGF-1 LR3 — zero records.
  2. Search ClinicalTrials.gov for the analogue — no studies.
  3. Run "IGF-1 LR3"[tiab] OR "IGF-I LR3"[tiab] OR "LR3 IGF"[tiab] OR "Long R3 IGF-1"[tiab] in PubMed and read all 44 titles. Count the human ones.
  4. Open the INCRELEX label on DailyMed and read section 2.1 — note that every figure carries "/kg" and "twice daily".
  5. Look up any human figure a research page cites and check whether it names a study at all.

Our CJC-1295 and ipamorelin page covers the growth-hormone secretagogues, which act upstream of IGF-1 by a different mechanism. How to read a dosing claim sets out the checks that catch an untraceable figure, and MuscleLedger's IGF-1 LR3 coverage approaches the same compound from a performance angle.

Sources and dates

Opened 2026-09-11: the DailyMed SPL search API for IGF-1 LR3 (zero records) and for mecasermin (INCRELEX, Ipsen Biopharmaceuticals, setid a8b27a1b-a611-4f91-ad22-76d4b390c3ae), from which the labelled dose range, titration, maximum, meal timing, glucose-monitoring requirement, contraindications and warnings are taken verbatim; the ClinicalTrials.gov v2 API for IGF-1 LR3 (no studies) and for mecasermin (40 studies, none of the analogue); PubMed through the NCBI E-utilities for "IGF-1 LR3"[tiab] OR "IGF-I LR3"[tiab] OR "LR3 IGF"[tiab] OR "Long R3 IGF-1"[tiab] (44 records, zero under the randomised-controlled-trial filter), with all 44 summaries retrieved and classified by hand into the groups in the table above. The 2025 fetal-sheep paper and the 2023 insulin-secretion paper are named in full in that record set. Corrections go to the contact page.

Frequently asked questions

What is the standard IGF-1 LR3 dose?

There is no standard in any regulatory or published sense. No approved label mentions the analogue, no trial has been registered for it, and the 44 indexed papers contain no human study to borrow a figure from. Figures circulate on research pages in the range of 20 to 50 micrograms per day; we could not locate a source that traces any of them to a published human result. This page reports that absence rather than filling it.

Isn't IGF-1 LR3 just IGF-1?

No, and the difference is the whole point of the molecule. Long R3 IGF-1 carries an arginine substitution at position 3 plus a 13-amino-acid N-terminal extension, engineered to reduce binding to the IGF-binding proteins that normally sequester circulating IGF-1. That is why it works so well as a cell-culture supplement, and it is also why a figure worked out for native IGF-1 cannot simply be scaled to it — the two molecules differ precisely in how much free compound a given quantity produces.

What does the approved IGF-1 product state?

INCRELEX (mecasermin) is recombinant human IGF-1, approved for growth failure in children two and older with severe primary IGF-1 deficiency or a growth-hormone gene deletion with neutralising antibodies. Its labelled dose is 0.04 to 0.08 mg/kg of body weight twice daily by subcutaneous injection, titrated by 0.04 mg/kg increments to a maximum of 0.12 mg/kg twice daily, with preprandial glucose monitoring. It is a different molecule, for a different population, dosed by weight rather than as a flat figure — the comparison is offered as context for what a reviewed IGF-1 dose looks like, not as a conversion.

Why is the hypoglycaemia point on this page?

Because it is the one effect the published record connects across species. The INCRELEX label records severe hypoglycaemia leading to hypoglycaemic seizures and requires dosing around a meal with glucose monitoring. Independently, a 2023 fetal-sheep study reported attenuated glucose-stimulated insulin secretion during an acute IGF-1 LR3 infusion. Those are different molecules in different species and neither establishes anything about a human taking the analogue; what they show is that the glucose axis is where the measurable effects sit, in both the approved product and the analogue's own animal literature.

Is there really no human research at all?

Not in the indexed literature under the analogue's names. We retrieved all 44 title-and-abstract records and read them: the largest group is reproductive cell culture, then in vivo work in sheep, cattle, pigs and turkeys, then cancer cell lines, then rodents, then protein-expression methodology. A reader can reproduce this in a few minutes and reach the same count. What that absence does not prove is that the analogue does nothing — it means the human dose-response relationship is not something anyone can currently examine.

What does a stated microgram figure look like in a syringe?

It depends entirely on the reconstitution. A 1 mg vial in 1 mL of bacteriostatic water gives 1,000 micrograms per millilitre, so a stated 20 micrograms is 0.02 mL — 2 units on a U-100 insulin syringe. At that volume the syringe's dead space and the accuracy of a two-unit mark become significant fractions of the quantity, which our syringe page works through. Our reconstitution page carries the arithmetic for other vial-and-volume combinations.